1. Field of the Invention
This invention relates to a reader-printer provided with a reflection type screen.
2. Description of Prior Art
The existing film readers for magnifying and projecting images recorded on microfilm are classified into two types according to their reading systems. One of the types is called the "transmission type" which uses a so-called transmission type screen comprising a light-diffusing layer provided on one surface of a plate formed of transparent glass or transparent acrylic resin, and in which a magnified image of the microfilm is projected upon the rear surface of the screen, while the light transmitted through the screen is read on the front surface of the screen. The other type is called the "reflection type" which uses a so-called reflection type screen comprising a flat plate having a light-diffusing surface like that of the movie screen, and in which a magnified image of the microfilm is projected upon the front surface of the screen, while the light reflected by the screen is read on the front surface of the screen. In the former type, the light transmission factor is poor due to the light-diffusing layer, on account of which the surface of the viewing screen is dark, and also as the diffusibility is low, the marginal area of the viewing screen is illegible unless the viewer shifts his eye position. Moreover, the surface of the viewing screen is so dazzling as to fatigue the eyes of the viewer. In contrast, the latter reflection type screen eliminates these disadvantages and makes it easier to view the image on the screen.
In any of the reader-printers provided with such screen, a rotatable mirror is provided to project an image of the film alternately onto the screen and the printing section, and, by rotating the mirror, the image is projected upon the screen for viewing, or printing by further projecting the image upon the printing section. This necessitates two optical paths, one leading from the mirror to the screen, and the other leading from the mirror to the printing section. Moreoever, when the image of the microfilm is to be magnified and projected, the optical paths become very long. As such, the entire device inevitably and disadvantageously becomes large-sized and complicated. A further disadvantage in these known devices is that since the mirror is moved, there takes place a deviation of the mirror from its proper position during its alternate image projections with the consequent halation of the projected images on the screen and the printing portion.